1. Field of the Invention
This invention relates to apparatus and methods used for sorting produce or other items according to size, and more particularly to an apparatus and method for hydraulically adjusting the space between the rollers on a conveyor to permit optional uniformly graduated increments or fixed spacing between each pair of rollers.
2. The Prior Art
In many industries there is a need to automatically sort items according to size. For example, in the agricultural industry, one common method for sorting objects according to size is to place the objects on a conveyor which consists of a series of rollers. The surface of the rollers and the slope or incline at which the conveyor is placed permits the various items of produce placed on the conveyor to be transferred from one end of the conveyor to the other. Depending upon the size of the space between each pair of rollers, produce which is a certain size and smaller will fall through the spaces between the rollers, whereas larger items of produce will continue to be carried by the rollers to the end of the conveyor. In this manner, the roller conveyor automatically sorts the produce according to size.
In order to be able to change the size of produce which is permitted to drop through the roller conveyor, there is a need to be able to adjust the space between rollers. The ability to adjust the spacing between rollers is important because it permits the conveyor to be used for a much wider variety of products, as well as permitting the conveyor to be used for sorting various sizes of a particular product. There have been several attempts in the art to address this particular need.
One attempt which has been made in the prior art involves the use of a frame which is used to support the rollers, and providing on the frame a series of holes which can be selected for each roller. Each roller is then secured to the frame by placing a bolt through the selected hole and then securing the bolt with a nut. By providing a series of holes the location of each roller can be changed as desired so that spacing between rollers can be increased or decreased to permit sorting of larger or smaller items, as needed. While this particular methods works for purposes of permitting the conveyor to be adjusted and used for sorting different sizes, the disadvantage of this method is that there is a good deal of manual labor involved in having to undo and resecure each individual roller. Thus, it is very time consuming and inconvenient, as well as creating costly downtime in order to make the needed adjustments.
Another approach which has been used in the art to vary the spacing between rollers is to provide coil springs which are compressed between each pair of adjacent rollers. By increasing the distance between the first and the last rollers on the conveyor, the coil springs will automatically expand the distance between all adjacent rollers so as to increase the space between them. While this particular approach permits more rapid adjustment when increasing or decreasing the space between adjacent rollers, it has the disadvantage that the space between each pair of rollers will be uniform. In some circumstances, it is desirable to have different size spaces between the roller at opposite ends of the conveyor so that smaller items will be sorted at one end of the conveyor while somewhat larger items will be sorted at the other end of the conveyor. Another disadvantage of this approach is that items can get caught between the rollers, forcing them apart. This results in nonuniform sorting.